This question is an exact duplicate of:
Today I installed Kali Linux via bootable USB, and during installation there was a problem installing the bootloader. So I skipped its installation and restarted my computer. But GRUB couldn't find the Kali Linux installed on my logical partition
sda4, i.e., it didn't show the option to boot to Kali Linux.
Moreover, during my installation, I set the bootable flag as "no", and I don't know whether it will have any effect on the boot.
I have presently three operating systems installed on other partitions (Windows 7, Linux Mint 17, and Linux Mint 17.2) and today Kali. Installation was also completed.
So how do I boot to Kali Linux now??
This is the result after I tried the command
Generating grub configuration file ... Found linux image: /boot/vmlinuz-3.18.2-031802-generic Found initrd image: /boot/initrd.img-3.18.2-031802-generic Found linux image: /boot/vmlinuz-3.13.0-24-generic Found initrd image: /boot/initrd.img-3.13.0-24-generic Found memtest86+ image: /boot/memtest86+.elf Found memtest86+ image: /boot/memtest86+.bin No volume groups found Found Windows 7 (loader) on /dev/sda1 Found Linux Mint 17 Qiana (17) on /dev/sda7 done